Hillsborough County sheriff's officials said around 1:30 p.m., the woman left the MD & More Clinic on the corner of W Hillsborough Avenue and Town 'N Country Boulevard.

Sheriff's spokeswoman Debbie Carter described what happened next this way:

As the woman came outside, a man grabbed the pills she'd just bought and jumped into a tan Honda sedan with tinted windows. There was a blond woman behind the wheel.

In the parking lot, a bystander saw the thieves getting away and leaped through their rear window, trying to stop them.

The Honda roared off, banging into another vehicle and knocking the person off the car.

Nearby, Jason R. DeMarzian, 25, of Bradenton saw the chaos unfold and jumped on his motorcycle. He chased after the car as it raced west down Hillsborough Avenue.

Around the same time, a 2006 Ford Explorer pulled out the driveway of a Wing House restaurant.

DeMarzian's motorcycle hit it broadside, slammed to the pavement and caught fire.

Ryan Gorskie, 23, of Tampa is the general manager of Mattress Doctor. He was at his desk working when he heard the sickening thump of a bad collision outside.

He ran out the door, already dialling 911 on the store's cordless phone.

He said he saw that the motorcycle was on fire. The rider was on the ground, not moving.

Gorskie said both the biker's legs obviously were broken.

The couple inside the SUV, Tony and Kelly Agan, covered their faces in shock, he said.

A driver jumped out of a nearby car, grabbed DeMarzian under the arms and dragged him away from the burning cycle. Others in the gathering crowd told him to stop moving the victim.

A few cars back, another man got out of a marked county vehicle and put out the flames with a fire extinguisher.

Four other people, including a 20-year Tampa police veteran who was buried Wednesday, have died in motorcycle-related crashes in the past two weeks.

Like Master Patrol Officer Victor Guerrero, DeMarzian was not wearing a helmet.

The driver of the Explorer, Tony Agan, turned 29 Wednesday. Neither he nor his wife, who was a passenger in the SUV, returned a call from a Times reporter. No one answered the door at their Carrollwood home.

Meanwhile, officers continue to investigate the theft. Citing privacy laws, officials wouldn't disclose the type of drug the woman bought, and said they weren't sure why the robbers targeted her.

The suspected thief is described as a 6-foot-2, 175-pound white man in his 20s or 30s with a beard. He wore a blue dress shirt, jeans and blue hat.

The driver of the Honda is described as a 5-foot-5, 130-pound white woman with long blond hair. She wore a white shirt and shorts. The Honda had no tags.

Anyone with information is asked to call the Hillsborough County Sheriff's Office at (813) 247-8200 or Crime Stoppers at (800) 873-TIPS.

Times researcher John Martin and staff writer Justin George contributed to this report. Rodney Thrash can be reached at rthrash@sptimes.com or (813) 269-5303.